docs: def _compute_anom_score_between_two_windows(self, i):
          """
          Compute distance difference between two windows' chunk frequencies,
          which is then marked as the anomaly score of the data point on the window boundary in the middle.
          :param int i: index of the data point between two windows.
          :return float: the anomaly score.
          """
          lag_window_chunk_dict = self.lag_dicts[i]
          future_window_chunk_dict = self.fut_dicts[i]
          score = 0
          for chunk in lag_window_chunk_dict:
              if chunk in future_window_chunk_dict:
                  score += math.pow(future_window_chunk_dict[chunk] - lag_window_chunk_dict[chunk], 2)
              else:
                  score += math.pow(lag_window_chunk_dict[chunk], 2)
          for chunk in future_window_chunk_dict:
              if chunk not in lag_window_chunk_dict:
                  score += math.pow(future_window_chunk_dict[chunk], 2)
          return score